St. Charles Borromeo Seminary is the official seminary of the Roman Catholic Archdiocese of Philadelphia. The Ryan Memorial Library, which serves the Seminary College, Theology, and Religious Studies Divisions, contains over 135,000 volumes, A/V materials, and 500 current periodicals. Subject strengths include philosophy, patristics, systematic and moral theology, and Sacred Scripture. Historical materials are found in the Library's 17,000 volume Rare Book Collection, along with special collections of Catholic devotional literature, liturgical books, and catechisms.